Researchers in Canada used cadaver limbs to study the effects of hoof angles and loading patterns on joint surface contact areas in the fetlock. Eight limbs from Standardbred horses that died for reasons unrelated to this study were fitted into a mechanical pendulum device to simulate hoof strike at a trot. Strips of pressure-sensitive film were placed across the joint surfaces inside the fetlock to measure contact areas, and the limb was loaded while simulating flat, toe-first and heel-first landings.
On impact, fetlock joint loading primarly occurs between the long pastern and the cannon bone with greatest contact area on the dorsal aspect of the medial condyle. This is the area where cartilage is most affected in joint disease. Toe-first landings produced the greatest contact areas followed by flat- and heel-first landings. There seemed to be a slight dorsal shift in fetlock joint contact area from heel- to flat- to toe-first strike, but these differences were not significant.
It seems clear that while hoof landing patterns should theoretically affect fetlock joint loading, the effects are likely to be very attenuated by the time they reach the fetlock and are difficult to demonstrate in the laboratory.
— McCarty CA et al. EVJ 2015;47:715-720.
Magnetic resonance imaging (MRI) was used to diagnose and describe deep digital flexor tendon injuries in the foot and distal pastern area of horses presented to a veterinary teaching hospital over a 10-year period, and follow-up information was used to…